The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to form switching power supply controllers. In most cases, the switching power supply controllers included an over-voltage protection circuit to protect the controller and the load from over-voltage conditions in the output voltage. Typically a lower power transistor was enabled during the over-voltage condition in order to quickly discharge the output inductor of the power supply. During the discharge, the energy stored in the inductor sometimes caused the output voltage to go negative. The negative going voltage often resulted in damaging the load and damaging the semiconductor device that was driving the inductor. One example of such a power supply controller was a MAX1777 produced by Maxim Integrated Products of Sunnyvale Calif.
Accordingly, it is desirable to have an over-voltage protection circuit that protects the semiconductor device from the over-voltage condition, and that does not cause a negative load voltage.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention.